The present invention relates to the processing of vulcanised rubber which, with the intention of a regeneration for a new vulcanization operation or other utilization, is required to be crumbled by grinding into relatively fine particles.
Grinding mills with two toothed plates which work together face to face, are already known, one face of which is fixed and the other is driven in rotation, with a central supply across the said fixed plate, of material to be ground and peripheral removal of the ground products. In such mills, a cooling fluid, generally air, is injected between the two plates and in an intermediate radial position, by means of at least one injector which passes through the fixed plate. This type of grinding device can theoretically be used to grind rubber but experience shows that in certain grinding areas overheating occurs which is prejudicial to the good chemical and physical behavior of the product thus processed, and it has been confirmed, through experience, that the loss of air injected in situ between the plates cannot in any case be sufficient to reduce the overheating in question since this loss is necessarily very limited.
One object of the invention is to provide a method for grinding of the above-mentioned type, in which this disadvantage is minimized or substantially eliminated and where the temperature of the rubber during its passage through the grinder does not undergo any abnormal increase.
Another object of the invention is to provide a method of grinding where the disadvantages associated with the presence of oxygen in the air or of ozone formed at the grinding level are avoided.